For example, it took Path's first version one year to reach 1,000,000 downloads. Now, less than two months after its relaunch, the app has been downloaded 2,000,000 times (it's also a much better app this time around).

Fab's first iteration was a failure, but since its relaunch in April it reached 1 million users no sweat.

We looked at today's hottest startups and found when they crossed the 1,000,000 user or download milestone. We also threw in a few big tech companies like Facebook and Twitter for the sake of comparison.

Note: Websites and apps measure their growth with different metrics, so each startup can't be directly compared to another.